In recent years a number of industries have adopted the bag-in-box concept for storing and transporting liquid and particulate commodities in relatively large quantities. For example, the bag-in-box has been employed for transporting in bulk such diverse products as vegetable oils, salad dressings, syrups, soy sauce, peanut butter, pharmaceuticals, talc, motor oil, industrial chemicals, detergents in liquid or powder form, and toiletry products or ingredients. The bag-in box concept comprises a flexible bag that is chemically resistant and impermeable to water and air and serves as the container for a selected commodity, and a box that serves as a protective container for the bag and its contents. By way of example, a bag used for shipping commodities in bulk typically may have a volume in the order of 60 cubic feet and include at least a drain fitting whereby its contents may be removed. Some bags are formed with a second fitting for use in filling the bag.
The outer box is provided with a discharge opening near or at its bottom end through which the liquid or particulate contents can be discharged from the bag via its drain fitting. That discharge opening may be fitted with another drain fitting that mates with or accommodates the drain fitting of the bag, whereby to assure that material discharged from the bag will be directed to the intended receiving facility and prevented from accumulating in the bottom of the box. Where the bags have two fittings, the filler fitting is usually located at or close to the top end of the bag. The protective box usually comprises a cover or top panel that is removable to permit access to the bag.
An important financial consideration of the bag-in-box mode of shipment of materials in bulk is that it can be a non-returnable or one-way container, in which case the box is generally made of a corrugated fiberboard or the like which can be discarded after use. Alternatively, the outer box may consist of interlocking panels of metal, wood or a stiff or rigid plastic material, in which case the box may be disassembled and returned to the shipper after the associated bag has been emptied of its contents.
Further with respect to the bag-in-box concept as applied to bulk shipment of commodities, the plastic bags have taken various forms, including the so-called “pillow” type which consists of two sheets of plastic film sealed together at their edges and four sided bags made from a plurality of sheets of plastic film, e.g., bags that take the shape of a cube or rectangular parallelepiped when filled. A specific form of four sided bag is disclosed in U.S. Pat. No. 5,788,121, issued Aug. 4, 1998 to H. Sasaki et al. Regardless of the type of bag in the box, if the bag is large, e.g., a bag having a volume of about 275 gallons, complete removal of all of the liquid or particulate material from the bag is difficult. The problem of removing all of the contents is noticeably difficult in the case of viscous liquids. Depending on the form of bag construction, complete emptying of the bag may be impeded by its size or shape, the location of its drain and/or the fact that as its contents are discharged, the evacuated portion of the bag tends to collapse.
Heretofore efforts have been made to provide means for supporting and tilting the plastic bags as they are being emptied via their drain fitting, so that the drain fitting is kept flooded with the viscous or particulate contents. One such effort is disclosed in U.S. Pat. No. 5,765,723, issued Jun. 16, 1998 to D. E. Wilcox. The Wilcox invention consists of a windlass that is mounted on the box and has a connector cord that is attached to a gathered portion of the bag by a noose. Operation of the windlass serves to lift and draw the gripped portion of the bag across the container toward the drain side of the container, and subsequently to wind the gripped portion of the container onto the windlass shaft. The result of the bag lifting and winding process is to move the viscous liquid material more effectively toward the drain.
However, a problem arises in using the Wilcox invention for emptying plastic bags that have a generally cubic or rectangular parallelepiped shape when filled, e.g., substantially self-supporting bags like those disclosed in U.S. Pat. No. 5,788,121, cited supra, since those bags are difficult to grasp with a noose. One proposed solution was to make a cube-shaped or rectangular parallelepiped bag by providing a plastic tube having a square or rectangular cross-sectional configuration and attaching top and bottom panels of like plastic material to the opposite ends of the tube by means of heat seals, with the bottom wall panel conforming in shape and size to the bottom end of the tube and the top end panel differing from the bottom panel in that at one side it projects laterally outward of one side of the rectangular tube so as to provide a tab portion that can be grasped to support the bag as it is being emptied via a drain provided at the bottom end of the tube. The tab portion is long enough to be wrapped on itself around the windlass shaft, whereupon further rotation of the windlass shaft produces a lifting force on the bag that results in the bag's contents being urged toward the drain by gravity.
Unfortunately the structural integrity of the foregoing tab construction is limited by the strength of the seal made by the end panels with the ends of the tube. Those seals are narrow and when the tab is wound on the windlass shaft, the weight of the bag and its contents tend to stress the top end panel to the extent that it may tear or separate where it is joined to the tube. That method of making a bag with a flap is labor intensive and hence costly.
Accordingly it is desirable to provide a new and improved tab construction that is characterized by a structural integrity sufficient to support the weight of a bag and its contents as it is being wound on a windlass.